Question

IM使用BlockingObservable遇到了一个难题。我有一种情况，我需要回调完成，完成后我可以进行改造API调用以获取数据。具体来说，我需要首先初始化支付网关sdk，然后在成功初始化后，我将进行改装调用。以下是我到目前为止的情况：

  Observable.fromCallable(new Callable<PaymentStrategy>() {

                    @Override
                    public PaymentStrategy call() throws Exception {
                        return gatewayFactory.getPaymentStrategy("US");
                    }}).flatMap(new Function<PaymentStrategy, ObservableSource<PaymentStrategy>>() {
                    @Override
                    public ObservableSource<PaymentStrategy> apply(@NonNull final PaymentStrategy paymentStrategy) throws Exception {
                        return Observable.fromCallable(new Callable<PaymentStrategy>() {
                            @Override
                            public PaymentStrategy call() throws Exception {


        /*here is important. i want it to block until init actually
     gets a call back. when it does the subscriber will call
 onComplete and the observable should move forward at that point*/


                                paymentStrategy.init(paymentInitSubscriber);
                                return paymentStrategy;
                            }
                        });
                    }}).observeOn(AndroidSchedulers.mainThread())
                        .subscribeOn(AndroidSchedulers.mainThread())
                        .subscribe(paymentInitSubscriber);

似乎rxjava2没有toBlocking（）调用，但我确实找到了toBlockingFirst（）等和BlockingObservable类。但我不知道如何完成任务仍然。所以要明确的是，当我调用paymentStrategy.init（）时，我需要observable才能阻塞，直到调用订阅者onComplete或onNext。我将订阅者作为参数传递，以便回调知道在完成时调用它。任何想法？

Answer 1

我发现我最好使用Flowable并为它提供发射器。然后我可以发出onNext和onComplete等事件。

final PaymentStrategy paymentStrategy = gatewayFactory.getPaymentStrategy("US");

            FlowableOnSubscribe flowableOnSubscribe = new FlowableOnSubscribe() {
                @Override
                public void subscribe(FlowableEmitter e) throws Exception {
                    FlowableEmitter initdownFlowableEmitter = e;
                    paymentStrategy.init(e);
    /* above i pass in the emitter and i can call onNext when the call back i want completes. this pushes the stream forward to the next one below of the retrofit call */
                }
            };

            final Flowable flowable = Flowable.create(flowableOnSubscribe, BackpressureStrategy.BUFFER);
            return flowable.flatMap(new Function() {
                @Override
                public Object apply(@NonNull Object o) throws Exception {
                    PaymentApi service = mRetrofit.create(PaymentApi.class);
                    return service.getCards();
                }
            }).toObservable();

并且不要忘记在改造类中使用Flowable而不是obtableable。

似乎fromAsync已根据github notes here重命名为Flowable.create：

实际上，1.x fromEmitter（以前来自async）已重命名为Flowable.create。

rxjava2 - 如何阻止直到回叫完成然后再进行改装调用？

1 个答案: